This invention relates to apparatus adapted to be quickly connected to electric motor driven lifting conveyors and which can be quickly adjusted to measure and indicate immediately the load delivered by the conveyor. More particularly, the invention relates to apparatus which is compact, light weight, and readily portable for use with a multiplicity of conveyors.
Apparatus for measuring the tonnage carried by lifting conveyors is known; and one form of such apparatus is described in applicant's U.S. Pat. No. 3,722,660 issued Mar. 27, 1973. The apparatus disclosed in that patent is inherently bulky and cumbersome, not adapted to be readily connected to and disconnected from the conveyor, and therefore limited for use on permanent installations, or for use where the measuring apparatus is to remain connected to the conveyor for an extended period such as several days.
It is desirable that portable measuring apparatus be available for use in a large plant, such as quarrying operation, or in any other plant wherein a multiplicity of conveyors or conveyor systems are employed for the handling of bulk materials and where it is necessary to ascertain and record the load output from such conveyors. In situations where it is required to record the entire load output for the conveyors, but where only certain of the conveyors are being operated at any given time, with the use of portable measuring apparatus, a lesser number of such apparatus may be employed for ready connection to the several systems in use when they are used. This will obviate the necessity for having a separate measuring apparatus for each conveyor. In a situation where it is not necessary to fully measure the output of each conveyor, but only to monitor occasionally the output of a conveyor, it will be apparent that the expense of measuring systems can be minimized with the use of portable measuring apparatus which is readily connectable to a plurality of conveyors.
A principal object of this invention is to provide measuring apparatus adapted for use in monitoring a plurality of conveyors, and therefore adapted for quick connection to and disconnection from such conveyors and for quick calibration to the particular conveyor with minimum interference with the operation of the conveyor.
Another principal object of this invention is to provide such weighing apparatus in a compact and light weight package which can be readily and manually carried from one conveyor system site to another by a single operator.
Another object of this invention is to provide such apparatus which is very reliable and accurate.
A further object of this invention is to provide such conveyor measuring apparatus which is all electric and which has no moving parts.
These objects are accomplished in electric measuring apparatus for use with a lifting conveyor driven by an electric motor, which includes a solid state watt transducer, and means for coupling the transducer to the motor power supply conductors include means for feeding input voltage to the watt transducer proportional to the motor supply voltage and means for feeding an input current to the watt transducer proportional to the current drawn by the motor, whereby the watt transducer produces an output voltage proportional to the motor power consumption. A solid state transmitter coupled to the output of the transducer amplifies the transducer output voltage, and includes adjustment means for producing a zero output signal responsive to an input voltage of preselected value, and therefore produces an output signal proportional to the motor power consumption in excess of a selected power consumption. A solid state integrator is coupled to the transmitter for converting the transmitter output signal to voltage pulses of uniform value; and adjustment means coupled between the transmitter and the integrator adjust the value of the input voltage to the integrator. A counter coupled to the integrator output detects and records cumulatively the integrator output pulses.
The novel features and advantages of the invention as well as additional objects thereof will be understood more fully from the following description when read in connection with the accompanying drawings.